lack m3C modification in arginine tRNAs and reveal a biological link between m3C tRNA modification and proper neurological function.Table 1Clinical phenotype and molecular findings for patients with homozygous variants in DALRD3.Patient 1Patient 2ID19DG050919DG0510GenderMaleFemaleDate of birth17/04/200905/01/2013GenotypeNM_001276405.1:c.1251 C > A:NM_001276405.1:c.1251 C > A:Proteinp.(Tyr417*)p.(Tyr417*)Perinatal historyNormal spontaneous vaginal delivery with history of placental insufficiency and oligohydramniosFull term product of cesarean section due to breech presentation and oligohydramnios in addition to placental insufficiencyWeight at birth (kg)2.25 (−2.2 SD)2.5 (4th centile)Developmental delaySevereSevereMotorImmobileImmobileSpeechNonverbalNonverbalSeizuresSeizures started at age 7 months in the form of myoclonic jerks which remains frequent and poorly controlled by antiepileptic medicationsAt age 6 months epilepsy ensued, initially as brief episodes of flexion tonic spasm of head followed by myoclonic seizures. Unlike the sibling brother, the epilepsy of patient 2 is reasonably controlled by antiepileptic medications.EEGIndependent multifocal epileptic discharges predominantly over the anterior head region bilaterally as well as over the right temporal and right parietal regionsMarkedly high voltage and slow background for age along with slow generalized polyspike and wave activityToneAxial and peripheral hypotonia with dystonic like movement and generalized muscle wastingCentral and peripheral hypotonia with dystonic like movements and generalized muscle wastingMicrocephalyNoYesBrain findingMild diffuse brain parenchymal volume loss with diffuse paucity of the myelin
